Pipe coupling plug



FIG. 1 is a perspective view taken from the top, front and left side of a pipe coupling socket showing our new design;

FIG. 2 is a front elevational view thereof, the rear being a mirror image of the front;

FIG. 3 is a top plan view thereof, the bottom being a mirror image of the top;

FIG. 4 is a left side elevational view thereof; and,

FIG. 5 is a right side elevational view thereof. 

The ornamental design for pipe coupling plug, as shown and described. 